1. Technical Field of the Invention
The present invention generally relates to the telecommunications field and, in particular, to an intelligent roaming mobile station and method for emulating a pre-intelligent scanning routine used by a pre-intelligent roaming mobile station.
2. Description of Related Art
A portion of the service providers that currently provide cellular telephone services to subscribers operate cellular telecommunications networks based on the Personal Communication Services (PCS) standard and, more specifically, the IS-136 standard. Each PCS telecommunications network is assigned a service band having a particular frequency range for use by the subscribers. The PCS standard provides for two service bands (e.g., "a" and "b" service bands) in the 800 MHZ spectrum, and six service bands (e.g., "A", "B", "C", "D", "E" and "F" service bands) in the 1900 MHZ spectrum.
The subscriber receiving cellular telephone service from one of the PCS telecommunications networks generally uses a mobile station having an intelligent roaming database (IRDB) and an intelligent roaming scanning routine (IR scanning routine). These mobile stations are referred to as IR mobile stations. The IR scanning routine of the IR mobile station is activated whenever the subscriber is "roaming" and operates in a manner to locate the one service provider that offers the best service. Of course, the one service provider that offers the best service is generally the one which also provides the least expensive services.
Prior to the implementation of the PCS standard and the availability of the IR mobile station, service providers were assigned one of the two service bands in the 800 MHZ spectrum on which to provide cellular telephone services. These service providers are referred to as 800 MHZ service providers. During this period, the subscribers used pre-intelligent roaming mobile stations (pre-IR mobile stations). The pre-IR mobile station includes a legacy database and a pre-intelligent roaming scanning routine (pre-IR scanning routine) for locating a particular 800 MHZ service provider whenever the subscriber is roaming.
Today several of the 800 MHZ service providers are still in the business of providing cellular telephone services to subscribers that use pre-IR mobile stations in addition to the newer IR mobile stations. Some of these 800 MHZ service providers want to maintain the look and feel of a traditional menu associated with the pre-IR mobile stations within the newer IR mobile stations. The traditional menu enables roaming subscribers to select 800 MHZ service providers.
To accommodate the 800 MHZ service providers that desire to maintain the traditional menu, IR mobile stations can be manufactured to include not only the legacy data base and pre-IR scanning routine associated with pre-IR mobile stations but also the IRDB and IR scanning routine. Using the retrofitted IR mobile station, the subscriber is then able to select either the pre-IR scanning routine using the traditional menu or the IR scanning routine using another menu. Unfortunately, these retrofitted IR mobile stations include two different databases and two different scanning routines to satisfy the small portion of 800 MHZ service providers that want to maintain the traditional menu. Of course, the maintenance of two scanning routines is unsatisfactory for obvious reasons.
Accordingly, there is a need for a method and intelligent roaming mobile station that emulates a pre-intelligent roaming mobile station's scanning routine while continuing to offer the menu used by the pre-intelligent roaming mobile station. There is also a requirement to provide an intelligent roaming mobile station that does not require the maintenance and support of two separate scanning routines. These and other needs are addressed by the intelligent roaming mobile station and method of the present invention.